1. Field of the Invention
The present invention relates to a power converter, especially to a power converter that can boost/lower an applied DC voltage by switching on/off a plurality of switch elements and charging/discharging a plurality of capacitors selectively.
2. Description of the Related Art
Japanese Laid-open Patent Application No. 2005-224059 and Japanese Laid-open Patent Application No. 2005-224060 disclose DC/DC power converters boosting and lowering an applied voltage by a desired voltage increase/decrease ratio by predetermined switch elements being switched. Looking to these DC/DC power converters, an overlap time for which a plurality of switch elements are kept switched on is appropriately adjusted when switch elements are switched in order to improve voltage conversion efficiency and miniaturize the size of the power converter.
These conventional DC/DC power converters disclosed in the above mentioned references perform any of a voltage boosting operation, a current-through operation and a regenerating operation by switching on/off a plurality of switch elements and charging/discharging a plurality of capacitors selectively.
These conventional DC/DC power converters have a current through function mode and are capable of outputting an applied voltage without being boosted in this function mode by switching switch elements. Furthermore, they have a current shut-off function mode and are capable of shutting off a current flowing to a capacitor in order to prevent too large a current from flowing to the capacitor by accident in this current shut-off function mode. This current shut-off function mode is enabled by a contactor box which is additionally installed in the conventional DC/DC power converter.